1. Field of the Invention
The present invention relates to a recording magnetic head used as a floating type magnetic head or the like, and more particularly, relates to a magnetic head capable of reducing series resistance of a coil layer.
2. Description of the Related Art
FIG. 19 is a vertical cross-sectional view showing a related magnetic head.
A magnetic head H1 shown in FIG. 19 is a so-called perpendicular magnetic recording head which applies a perpendicular magnetic field to a recording medium M so as to magnetize a hard film Ma of the recording medium M in a perpendicular direction.
The recording medium M has, for example, a disc shape, is composed of the hard film Ma having a high residual magnetization and located at a magnetic head H1 side and a soft film Mb having a high magnetic permeability and located at a side apart from the magnetic head H1, and is allowed to rotate around the center of the disc.
A slider 1 is formed of a non-magnetic material such as Al2O3.TiC, and a facing surface 1a of the slider 1 faces the recording medium M. When the recording medium M is allowed to rotate, due to an airflow generated along the surface thereof, the slider 1 floats above the surface of the recording medium M or slides on the surface thereof. In FIG. 19, the moving direction of the recording medium M with respect to the slider 1 is a direction indicated by an arrow A.
On an end surface 1b at a trailing side of the slider 1, a non-magnetic insulating layer 2 composed of an inorganic material such as Al2O3 or SiO2 is formed, and on this non-magnetic insulating layer 2, a reading portion HR is formed.
The reading portion HR has a lower shield layer 3, an upper shield layer 6, an inorganic insulating layer (gap insulating layer) 5 provided therebetween, and a reading element 4 provided in the inorganic insulating layer 5. The reading element 4 is a magnetoresistive effect element such as an AMR (anisotropic magnetoresistive effect), a GMR (giant magnetoresistive effect), or a TMR (tunnel magnetoresistive effect) element.
A plurality of second coil layers 8 composed of a conductive material such as copper is formed on the upper shield layer 6 with a coil insulating underlayer 7 provided therebetween.
Around the second coil layers 8, a coil insulating layer 9 is formed which is composed of an inorganic insulating material such as Al2O3 or an organic insulating material such as a resist.
On the coil insulating layer 9, an auxiliary yoke layer 21 is formed, and on this auxiliary yoke layer 21, a main magnetic pole layer 10 is formed which has a predetermined length L2 extending from a facing surface H1a in a height direction and a predetermined width in a track width direction (X direction in the figure) at the facing surface H1a, the width being equivalent to a track width Tw. The main magnetic pole layer 10 is formed, for example, by plating using a ferromagnetic material, such as Ni—Fe, Co—Fe, or Ni—Fe—Co, having a high saturated magnetic flux density.
On the main magnetic pole layer 10 and the auxiliary yoke layer 21, a gap layer 13 is formed using an inorganic material such as alumina or SiO2.
First coil layers 15 of copper or the like are formed on the gap layer 13 with a coil insulating underlayer 14 provided therebetween. The second coil layers 8 and the first coil layers 15 are electrically connected to each other at the respective end portions thereof located along the track width direction (X direction in the figure) and are wound around the main magnetic pole layer 10 and the auxiliary yoke layer 21, so that a solenoidal coil layer is formed.
Around the first coil layers 15, a coil insulating layer 16 is formed using an inorganic insulating material such as Al2O3 or an organic insulating material such as a resist, and a return path layer 17 is formed using a ferromagnetic material such as Permalloy so as to cover this coil insulating layer 16 and the gap layer 13.
At a rear side of a coupling portion 17b of the return path 17 in the height direction (Y direction in the figure), a lead layer 19 extending from the first coil layers 15 is formed on the coil insulating underlayer 14. In addition, the return path layer 17 and the lead layer 19 are covered with a protective layer 20 formed of an inorganic non-magnetic insulating material or the like.
In the magnetic head H1, when a recording current is supplied to the second coil layers 8 and the first coil layers 15 via the lead layer 19, by a current magnetic field of the current flowing through the second coil layers 8 and the first coil layers 15, a recording magnetic field is induced in the main magnetic pole layer 10 and the return path layer 17. At the facing surface H1a, a magnetic flux φ1 of the recording magnetic field flows from a front surface 10c of the main magnetic pole layer 10 and then sequentially flows through the hard film Ma and the soft film Mb of the recording medium M. After a recording signal is recorded on the recording medium M, the magnetic flux φ1 is returned to a front surface 17a of the return path layer 17.
A film thickness t1 of the first coil layer 15 is equal to or larger than a film thickness t2 of the second coil layer 8. A magnetic head having a coil layer of a solenoidal structure as described above has been disclosed, for example, in FIGS. 23 and 24 of US Patent Publication No. 2004/0012884 A1.
As is the case in the past, when the film thickness t1 of the first coil layer 15 is equal to the film thickness t2 of the second coil layer 8, due to heat generated from the coil, the facing surface facing the recording medium of the magnetic head is expanded and is liable to be brought into contact with the recording medium. In addition when the film thickness t1 of the first coil layer 15 is larger than the film thickness t2 of the second coil layer 8, a magnetic path length of a magnetic circuit of the magnetic head is increased, and as a result, recording efficiency is decreased. Hence, in a related magnetic head, improvement in recording properties has not been desirably performed, and in addition, the amount of heat thus generated is still large.